1. Field of Invention
The present invention relates to a power adapter, and more particularly to a power adapter with a heat sink device which is adapted to evenly disperse the heat from the power transforming unit in the insulating casing so as to prevent the heat from concentrating at a region of the insulating casing.
2. Description of Related Arts
Power adapters are known as an electrical bridging device for providing an interface between a power source and an appliance. A conventional power adapter generally comprises an insulating casing and a power transforming device sealedly disposed in the insulating casing. The power transforming device generally comprises a transformer and a PFC (power factor correction) choke, such that when the power transforming device is electrically connected to the power source, the power transforming device is arranged to convert an AC Power from the power source to a DC power for the appliance.
For example, the power adapter is arranged to bridge between the power source and a laptop such that the power adapter is adapted to convert a 110V AC voltage from the power source into a 16V DC voltage to the laptop. In addition, since AC voltage supplies in various countries, the input of the power transforming device is interchangeable to fit different AC voltages, such as 110V and 220V.
However, the conventional power adapter has several drawbacks. During operation, the power transforming device generates heat within the insulating casing. Since the power transforming device is sealed inside the insulating casing to prevent the user from being electric shock, the heat from the power transforming device is trapped in the insulating casing. Unlike other device, the power adapter cannot employ a dispersing fan for dispersing the heat in the insulating casing to outside. Therefore, the heat accumulated within the insulating casing will affect the normal operation of the power transforming device.
In addition, the power transforming device forms as a heat source within the insulating casing such that the wall of insulating casing right above the power transforming device will be heated up rapidly. Accordingly, the insulating casing is made of heat insulating material, such as plastic, having a tolerance up to 95° C., such that the insulating casing will not be melted at normal operation of the power transforming device.
However, since the power transforming device forms as a heat source, a surface of the insulating casing, which is right above the power transforming device, will be heated up substantially. Accordingly, the average surface temperature difference of the insulating casing is 5° C. when the operation of the power transforming device such that it is dangerous when the user touches the insulating casing. In addition, the heat applied on the particular region of the insulating casing will damage the insulating casing so as to loss the sealing insulation ability thereof.